Gas turbine engines include various thermal management systems that include heat exchangers and other associated flow control components that exchange heat generated by the gas turbine engine with bypass airflow. The gas turbine architecture for each different type of engine determines where heat exchangers are located. In certain locations, the heat exchangers may partially block or disrupt thrust airflow. Further, conventional heat exchangers have a tendency to take up a significant amount of packaging area due to long duct transitions between the various system components.
In certain applications, heat exchangers with large square or rectangular frontal areas are required to provide specified operational characteristics. These heat exchangers are used with flow control valves that are positioned upstream of the heat exchanger, and which control an amount of air that is introduced into the heat exchanger. These valves have a circular shape and operate within relatively small duct sections that have a round cross-section. The transitions between the round and rectangular sections are long and complex, making it difficult to effectively package the components, and can also result in flow distortion leading to reduced engine operating efficiencies.